OK, Bill, here goes.
I use a pilots calculator I got from Shorty's Airplane Supply Co. It was about
$69.00. You will need a centigrade thermometer $18.00 and an altimeter ( got a
recalibrated one from Wicks Aircraft for $150), leave the barometer adjustment
set on 29.4. This will give you corrected density altitude. I used this type set
up for over 20 years drag racing with good results. I also have a wet/dry bulb
thermometer I bought used for $90.
In my mind, if I were to do this today, I'd buy the Computech Systems #3000
RaceAir Competition Weather Station for $349.95. It features automatic air
sampling and raw values for temperture, relative humidity,and barometric
pressure
are displayed continuously. Automatic calulations values for air correstion
factor, density altitude, ait density ratio, vapor pressure, dry barometer, dew
point temperturecan be displayed on a rotating or fixed basis.
How can you beat this piece...$349.95!!! This is probably too much info for the
average person, but you learn fast have to use the data. Racing has come a long
way since the days of just using a air density gauge.
Try www.computechsys.com for more info!
Should of been a salesman, I guess. Hope this helps.
joe
Bill Bennett wrote:
> At this point in the message thread I would like to ask Joe Timney to
> explain to the list what he uses at Maxton. He has explained it to me and
> seems to be a fairly simple method of determining air density. One thing
> about Davis Instruments is that with the use of a laptop and a free piece of
> software from them data can be downloaded directly to a spreadsheet or
> database program. This would allow air density to be automatically
> calculated. Pretty little things like graphs could be done on a daily basis.
> I wonder if there is a nominal rate of change in air density. I realize that
> drastic changes in the weather would effect the curve, but where day to day
> conditions didn't change much would it be possible say for this time of day
> its close to this and at another time of day say it is something else.
> Bill
>
> ----- Original Message -----
> From: "Henry Deaton" <hdeaton@verio.com>
> To: <ARDUNDOUG@aol.com>; <land-speed@autox.team.net>
> Sent: Sunday, December 30, 2001 11:05 PM
> Subject: Re: Climate data for the future...
>
> > What you get from our weather stations are the air's barometric pressure,
> > temperature, and humidity. From that you have to calculate air density.
> > There might be some special considerations in how you set it up as well
> > since the barometric pressure you'll see on our weather stations is
> > corrected for altitude and is a different reading than the actual air
> pressure.
> >
> > As far as I know, none of our products calculate density altitude
> directly.
> > Might not be too difficult to include density altitude calculations in a
> > future software release, but what do tuners really want? Plus, I'm
> actually
> > not sure I understand what density altitude is.
> >
> > Henry
> >
> >
> >
> >
> > >Henry,
> > > What does the $150 unit read out? Will it give density altitude, or
> > > do we
> > >have to take the altitude it gives and correct for temperature and
> humidity?
> > > My Jeb's is still on the original battery and I don't know if the
> > > battery
> > >can be replaced without losing the programming.
> > > If the $150 model doesn't read density altitude directly what's the
> cost
> > >of the unit that does?.......Ardun Doug King
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